This thing happened a lot in Naagin 3.
When fake Yuvraj was revealed to Vikrant. He was shown to be a victim when he went to Shiv's mandhir. And then few episodes after he was shown to be the perpetrator of the event that night. He even knew that Andy's sons and their friends will be there so that he could trick Bella into killing an innocent.Then when Anu was killed Vikrant said he did not kill Anu. He even asked whether the purple snake killed Anu. When the purple snake told her she did not kill Anu. He asked then who killed Anu. Then few episodes later we were shown that Anu was killed by the purple snake and Vikrant.There are a lot of loopholes and plot holes in Naagin 3. Especially if we compare to two previous seasons.